Jacquard

A suite of Rust crates intended to make it much easier to get started with atproto development, without sacrificing flexibility or performance.

Jacquard is simpler because it is designed in a way which makes things simple that almost every other atproto library seems to make difficult.

It is also designed around zero-copy/borrowed deserialization: types like Post<'_> can borrow data (via the CowStr<'_> type and a host of other types built on top of it) directly from the response buffer instead of allocating owned copies. Owned versions are themselves mostly inlined or reference-counted pointers and are therefore still quite efficient. The IntoStatic trait (which is derivable) makes it easy to get an owned version and avoid worrying about lifetimes.

Features

• Validated, spec-compliant, easy to work with, and performant baseline types
• Designed such that you can just work with generated API bindings easily
• Straightforward OAuth
• Server-side convenience features
• Lexicon Data value type for working with unknown atproto data (dag-cbor or json)
• An order of magnitude less boilerplate than some existing crates
• Batteries-included, but easily replaceable batteries.
  • Easy to extend with custom lexicons using code generation or handwritten api types
  • Stateless options (or options where you handle the state) for rolling your own
  • All the building blocks of the convenient abstractions are available
  • Use as much or as little from the crates as you need

0.9.0 Release Highlights:

#[derive(LexiconSchema)] + #[lexicon_union] macros

• Automatic schema generation for custom lexicons from Rust structs
• Supports all lexicon constraints via attributes (max_length, max_graphemes, min/max, etc.)
• Generates LexiconDoc at compile time for runtime validation

Runtime lexicon data validation

• Validation of structural and/or value contraints of data against a lexicon
• caching for value validations
• LexiconSchema trait generated implementations for runtime validation
• detailed validation error results

Lexicon resolver

• Fetch lexicons at runtime for addition to schema registry

Query and path DSLs for Data and RawData value types

• Pattern-based querying of nested Data structures
• data.query(pattern) with expressive syntax:
  • field.nested - exact path navigation
  • [..] - wildcard over collections (array elements or object values)
  • field..nested - scoped recursion (find nested within field, expect one)
  • ...field - global recursion (find all occurrences anywhere)
• get_at_path() for simple path-based field access on Data and RawData
• Path syntax: embed.images[0].alt for navigating nested structures
• type_discriminator() helper methods for AT Protocol union discrimination
• Collection helper methods: get(), contains_key(), len(), is_empty(), iter(), keys(), values()
• Index trait implemented: obj["key"] and arr[0]

Caching in identity/lexicon resolver

• Basic LRU in-memory cache implementation using mini-moka
• Reduces number of network requests for certain operations
• Works on both native and WebAssembly
• NOTE wasm target for mini-moka requires a git dependency, use the git version of the crate when compiling for wasm

XRPC client improvements

• set_options() and set_endpoint() methods on XrpcClient trait
• Default no-op implementations for stateless clients
• Enables runtime reconfiguration of stateful clients
• Better support for custom endpoint and option overrides
• Fixed bug where setting a custom 'Content-Type' header wouldn't be respected

Major generated API compilation time improvements

• Generated code output now includes a typestate builder implementation, similar to the bon crate
• Moves the substantial syn tax of generating the builders to code generation time, not compile time.

New jacquard-lexgen crate

• Moves binaries out of jacquard-lexicon to reduce size further
• Flake app for lex-fetch

Example

Dead simple API client. Logs in with OAuth and prints the latest 5 posts from your timeline.

// Note: this requires the `loopback` feature enabled (it is currently by default)
use clap::Parser;
use jacquard::CowStr;
use jacquard::api::app_bsky::feed::get_timeline::GetTimeline;
use jacquard::client::{Agent, FileAuthStore};
use jacquard::oauth::client::OAuthClient;
use jacquard::oauth::loopback::LoopbackConfig;
use jacquard::types::xrpc::XrpcClient;
use miette::IntoDiagnostic;

#[derive(Parser, Debug)]
#[command(author, version, about = "Jacquard - OAuth (DPoP) loopback demo")]
struct Args {
    /// Handle (e.g., alice.bsky.social), DID, or PDS URL
    input: CowStr<'static>,

    /// Path to auth store file (will be created if missing)
    #[arg(long, default_value = "/tmp/jacquard-oauth-session.json")]
    store: String,
}

#[tokio::main]
async fn main() -> miette::Result<()> {
    let args = Args::parse();

    // Build an OAuth client with file-backed auth store and default localhost config
    let oauth = OAuthClient::with_default_config(FileAuthStore::new(&args.store));
    // Authenticate with a PDS, using a loopback server to handle the callback flow
    let session = oauth
        .login_with_local_server(
            args.input.clone(),
            Default::default(),
            LoopbackConfig::default(),
        )
        .await?;
    // Wrap in Agent and fetch the timeline
    let agent: Agent<_> = Agent::from(session);
    let timeline = agent
        .send(&GetTimeline::new().limit(5).build())
        .await?
        .into_output()?;
    for (i, post) in timeline.feed.iter().enumerate() {
        println!("\n{}. by {}", i + 1, post.post.author.handle);
        println!(
            "   {}",
            serde_json::to_string_pretty(&post.post.record).into_diagnostic()?
        );
    }

    Ok(())
}

If you have just installed, you can run the examples using just example {example-name} {ARGS} or just examples to see what's available.

[!WARNING] A lot of the streaming code is still pretty experimental. The examples work, though.
The modules are also less well-documented, and don't have code examples. There are also a lot of utility functions for conveniently working with the streams and transforming them which are lacking. Use n0-future to work with them, that is what Jacquard uses internally as much as possible.
I would also note the same for the repository crate until I've had more third parties test it.

Changelog

CHANGELOG.md

Projects using Jacquard

• skywatch-phash-rs
• Weaver - tangled repository
• wisp.place CLI tool
• PDS MOOver - tangled repository

Component crates

Jacquard is broken up into several crates for modularity. The correct one to use is generally jacquard itself, as it re-exports most of the others.

jacquard	Main crate
jacquard-common	Foundation crate
jacquard-axum	Axum extractor and other helpers
jacquard-api	Autogenerated API bindings
jacquard-oauth	atproto OAuth implementation
jacquard-identity	Identity resolution
jacquard-repo	Repository primitives (MST, commits, CAR I/O)
jacquard-lexicon	Lexicon parsing and code generation
jacquard-lexgen	Code generation binaries
jacquard-derive	Macros for lexicon types

Development

This repo uses Flakes

# Dev shell
nix develop

# or run via cargo
nix develop -c cargo run

# build
nix build

There's also a justfile for Makefile-esque commands to be run inside of the devShell, and you can generally cargo ... or just ... whatever just fine if you don't want to use Nix and have the prerequisites installed.